Well bit protector



E T'. E. MGMAHAN WELL BIT PROTECTOR Sept. 29, 1942.

Filed` May 5, 1941 Patented Sept. 29, 1942 UNITED STATES y PATENT`OFFICE WELL BIT PROTECTOR Thomas E. McMQalian, Long Beach, Calif.

Application May 5, 1941, Serial No. 391,848

11 Claims.

This invention relates to well drilling tools and has particularreference to protectors for the bits employed in the rotary method ofwell drilling.I A-general object of the invention is to provide apractical, eiectivie and inexpensive protector 1'or well bits.

In the drilling of deep wells with the rotary method it is a commonpractice to employ roller rock bits. These bits embody toothed rollercutters supported at the lower end of the bitbody to independentlyrotate through contact with the earth formation as the bit is rotatedand fed downwardly. It is essential that the cutters be free to rotateand the speed of operation or efficiency of the bit is greatly .impairedif the teeth of the cutters become clogged with mud and cuttings. Inrunning a bit down through the Well to its operative position theexposed roller cutters accumulate mud and ball up and the mud 'gathersin the valleys between the cutter teeth. The mud or solid matter isscraped from the wall of the well bore as the bit descends and is pickedup or accumulated from the column of mud laden iluid standing in theWell. In many cases the bit is balled up by the time it reaches thebottom of the well bore and is thus made uneflicient before it goesintooperation. v

An important object of this invention is to provide a protector for awell bit which prevents the bit from accumulating mud, cuttings andother solid matter as it is run into the well.

Another object of this invention is to provide a well bit protectorwhich is effective in preventing the cutting parts of the bit fromaccumulating mud from the well fluid and in presive to manufacture andthat is readily shipped and transported.

Another object of the invention is to provide a bit protector of thecharacter mentioned that is easily and quickly applied to the bit whenthe same is to be run into the well.

A further object of this invention is'to provide a bit protector that isquickly drilled up,

venting the cutting parts from gouging, scraping or cutting mud vandearth formation from the wall of the well as the bit is being run intot'he well. The protector of the present invention not only shields thecutters against the mud v permits the free passage of uidbetween thecutters and body legs and into or through the well string so that itdoes not interfere with the free lowering of the bit through the well.

Another object of this invention is to provide a well bit protector ofthe character referred to that is extremely simple and inexpenwhen 'thedrilling operations are begun, to be reduced to small fragments that arereadily carried to the ground surface with the circulation iiuid.

The various objects and features of my invention will be fullyunderstood from the following detailed description of typical preferredforms and applications of my invention, throughout which descriptionreference is made to the accompanying drawing, in which:

Fig. 1 is a side elevation of a typical roller rock bit equipped withone form of protector of the invention. Fig. 2 is a plan view of theprotector shown in Fig. 1 in a flat or stretched out condition withbroken lines illustrating the positions of the bit cutters. Fig. 3 is aview similar to Fig. 2 showing another form of protector of theinvention arranged on the bit, and Fig. 4 is a fragmentary elevationstretch-out view of the under side of the protector shownin Fig. 3.

The protectors of the present invention may be designed for use on thevarious forms and types of well drilling tools. In the followingdetailed description I will describe typical embodiments of theinvention as employed on conventional roller rock bits. It is to beunderstood that the invention is not to be construed as vlimited orrestricted to the specicforms or. ap-

plications of the inventionl herein described.

The typical roller rock bit illustrated in thel vlower ends of the legsI3 to cut the well bore to gauge. 'I'he bit further includes crosscutters or inner cutters I6 rotatable about a general horizontal axisand supported between the legs I4 which are spaced about 90 from thelegs I3. The cutters I5 and|6 have the usual teeth I'I for acting on theearth formation at the bottom of the well bore and the body I has theusual circulation passage I8 and discharge ports.

'I'he protector of the invention illustrated in Figs, 1 and 2 may besaid to comprise, generally, a exible body 2|! to be engaged against thelower side of the bit, tabs or straps 2| on the body 20 adapted to betrained upwardly over the exposed toothed sliie parts of the outercutters I5, and means-22 for cooperating with the straps 2| to securethe protector to the bit. g

The protector body I0 is designed to engage upwardly against and shieldthe exposed or projectinglower parts of the cutters I and I6 and inpractice may be designed to cover substantially the entire lower side ofthe bit. In accordance with the invention the body is formed of aflexible, pliable and readily shaped material to be easily draped ortrained over the bit and to generally conform to the cutters I5 and I6.The invention contemplates the formation of the protector body 20 ofvarious materials and contemplates the construction of the body of anyinexpensive readily obtained and produced material that possesses therequired flexibility and that may be readily drilled up by the bit. Theprotector body 20 may be formed of fabric, rubber, rubber composition,synthetic rubber, ilexlble plastic, or the like, or combinations of suchmaterials. I may prefer to form the body 20 of undercured rubber with orwithout fabric as such material has the desired characteristics offlexibility, strength and low specific gravity and is readily broken upor ground up into small fragments by the bit. The material of which thebody 20 is formed preferably has a specific gravity comparable to orless than the specific gravity of the well fluid so that its particlesor fragments will be readily carried from the well by the well fluidwhen the bit is put into operation.

The protector body 20 is preferably, though not necessarily, in sheetform and may be a relatively thin member having upper and lower surfacesoccupying parallel planes. 'I'he shape of the sheet-like body `20, ofcourse, depends upon the type of bit on which it is to be used. In thecase illustrated the body III has two diametrically opposite edgeportions or edges 23 curved outwardly to substantially conform to theouter active edges of the cutters I5 when the protector is trained overthe bit. As illustrated in Fig. l of the drawing these edges 23 liewithin the cutting range or circumference of the cutter I5 and occurat-the outermost active edge parts of the cutter teeth I1 so that thebody serves to prevent the teeth from engaging the wall of the well andfrom accumulating mud as the bit is run down the well. The other edgeportions of the body 20 may be formed to merge with the straps 2|, asillustrated.

In accordance with the invention the body 20 of the `protector isporous, perforated or ported to permit th-e flow of fluid through thepassage I8 when the tool is run into the well. Those portions of thebody 2|) which lie under the channels or spaces occurring between thespaced adjacent legs I3 and I4 are porous, perforated or ported toprovide for the required flow of fluid to and from the passage I8. Inthe simple pre.- ferred construction illustrated the protector body 20has spaced ports 25 of substantial capacity located to communicate withthe spaces or channels occurring between the adjacent legs I3 and Il.The ports 25 are proportioned and arranged to allow the free iiow offluid upwardly vpast the bit and through the passage I8 when the bit isbeing run down through the well.

'I'he straps 2| are employed to retain the. protector in position on thebit and serve to shield or protect the exposed toothed portions of thebit cutters that are above the 'plane occupied by the bodyY 20. Thenumber and location of the straps 2| may vary with protectors intendedfor use on different styles and types of bits. In the particularapplication of the invention illustrated there are four straps 2|extending from the body 20. In the embodiment of the invention beingdescribed the straps 2| are integral with the body 20 being continuousextensions of vthe body. With this construction the complete protectormay be readily cut from a sheet of the selected material or stock. Asabove described, the margins or edges of the body 20 may merge with theedges of the straps 2|. With this formation the inner or lower portionsof the straps 2| are of increased width, as best shown in Fig. 2. Themajor upper portions of the straps -2| may have straight generallyparallel edges. The straps 2| are of sufficient length to extendupwardly to the shank or drill collar I2 of the bit.

In accordance with the invention the straps 2| are located to extendupwardly around or over the toothed portions of the cutters I5 which areexposed at the sides of the bit and the lower portions of the str-aps 2|are of suiiicient width to fully and eectively shield these portions'ofthe cutters and to close or cover the slots or spaces between the legsI3 and I4. 'I'his is clearly illustrated in Fig. 1 of the drawing whereit will be seen that the straps 2| engage upwardly around the cutters I5 to fully cover their toothed parts andextend across orcover the gapsbetween the cutters I5 and the legs I 4. Further, it will be observedthat the portions of the body 20 at the bases of the straps 2| alsocurve upwardly at the lower end of the bit to better protect the cuttersI5.

The means for attaching the protector to the well -bit may be variedgreatly Without departing from the broader aspects of the invention. Inthe simple case illustrated the means 22 comprises a length of cord,wire 26, or the like, wrapped or trained about the upper portion of thebit or the drill collar I2 thereof and engazed with the straps 2|. Ihave shown slots 21 formed in the upper parts of the straps 2| and haveshown the wire 26 threaded through the slots to have dependableengagement with'the straps. The ends of the wire 26 are tied or twistedtogether as at 28.

It is believed that it will be apparent how the protector in Figs. 1 and2 of the drawing may be easily and quickly secured in its operativeposition on the bit. The body 20 is merely engaged against the underside of the bit with its edges 23 in the correct relation to the cuttersI 5 whereupon the straps 2| are trained upwardly over the cutters I 5 tobring their upper parts to the shank or drill collar I2. The wire 26 isthen trained about the shank or drill collar I2 and tied or twistedtogether at 28. It is preferred to secure the protector so that the body2U and the straps 2| are tightly drawn on the bit to closely hug andconform to its cutters I5 and I 6 and other parts. The protector may beapplied to the bit immediately before running the bit into the well.When the bit is lowered through the well the body 20 and the straps 2|cover and shield the when the bit is operated to drill up the protector.

otherwise exposed toothed portions of the cutters -I and I5 and the gapsbetweenV the legs I3 and I4 so that they cannot accumulate mud. The body20 and straps 2| also serve to prevent the cutters from scraping,gouging or cutting into the side wall of the well bore and thus preventthe cutters from being clogged with the mud layer or earth formationfrom the well wall. The ports 25 permit the free upward ilcw of fluidinto the passage I l so that the protector does not obstruct the lowerend of the drilling string. When' theV bit reaches the bottom of thewell it is put into operation in the usual way. The toothed cutters I5and I5 quickly drill up the protector, the protector being cut orreduced to small fragments. These fragments are carried away by thecirculation iiuid and do.

not interfere with the drilling operation. The cutters I5 and I6 reachthe lower end of the well in a clean condition to operate at theirgreatest efficiency.

The form of the invention illustrated in Figs. 3 and 4 of the drawingmay be said to lcomprise, generally, a body 20, straps 2|l on the bodyand means 22B for securing the protector to the bit.

In the structure illustrated in Figs. 3 and 4 the body 2i)8L and thestraps 2|* are separately formed members. 'I'he -body 2li'l may be agenerally dat plate or disc-like part formed of a readily drillablematerial. The body 20* may be constructed of rubber, rubber composition,synthetic rubber, fabric or a combination of such materials or may beconstructed of Bakelite, plastic, or the like. It may be preferred toconstruct the body 20 of laminated material whose laminations arereadily separated and broken up when the bit is put into operation. Itis preferred to construct the body 2li8L of a material having a specificgravity comparable to or less than that of the well fluid. The body 20may possess substantial nexibility to conform to the cutters I5 and I6or may be fairly rigid. In the drawing the body 20 is shown flat whenengaged against the bit, it being understood that the body may besuiiiciently ilexible to be bent upwardly around the cutters I5 and I6when the protector is operatively secured to the bit. The protector body2lil is shaped and proportioned to fully cover the under sides of thecutters I5 and I6. In the particular case illustrated the body 20 hascurved edges 30 formed and positioned to lie fiush with or to conform tothe outermost active edges of the cutters IB.

As shown in Fig. 3 of the drawing these edges 3i)v occur at the lowerends of the cutters I5 and follow the outermost cutting edges of thecutters but do not project beyond the cutters. The body 2|)a may' havestraight edges 3| at the outer ends of the inner cutters I6. Theprotector body 20 is porous, perforated or ported to provide for acontrolled or directed circulation of iluid through the protector. Ihave shown four spaced ports 32 formed in the body 20 and located toregister with the Igaps or passages between the legs I3 and I4 of thebit.

It may be desired to roughen, corrugate or tooth the protector body 2liato assure the ready kdrilling up of the protector by the bitand' toprevent the protector from spinning in the well when the bit is put intooperation. In the construction illustrated there are corrugations orridges 33 formed on the upper side of the body 2U,a and positioned forengagement by the teeth of the cutters I5 and I6. 'I'he corrugations orridges 33 prevent the cutters from slipping or skidding over the surfaceof the protector body The under side of the body 20* may likewise beridged to have non-rotatable cooperation with the earth formation to thebottom of the well. In the case illustrated, however, the under side ofthe body 20* is provided with a central diametric ridge or blade 3l.'I'he engagement of the blade Il with the earth formation effectivelyprevents the protector from sliding or skidding when the bit is operatedto drill up the protector.

The straps 2|* serve the same function as the above described straps 2Ibeingoperable to protect or shield the otherwise exposed parts of thecutters I5, to close the otherwise open sides of the spaces between thebit legs I3 and I4, and to assist in securing the protector on the bit.The inner or lower ends of the straps 2|* are suitably fixed to the edgeportions of the body 20. The straps 2la may be riveted, pinned,cemented, vulcanized or stitched to the body 20, depending upon thenature of the materials of which the body and straps are constructed.The straps 2 I I may be formed of any selected flexible material that isdrillable and that will readily flush from the well. For example, thestraps 2|a may be formed of fabric, rubber, rubber composition,` orcombinations of such materials. The lower portion of the straps 2 I maybe thickened as at to better shield the toothed parts of the cutters I5which extend laterally beyond the legs I3. The straps 2ln are sumcientlylong to engage upwardly around the cutters I5 and the upper portion ofthe bit body III to have their upper ends at the bit shank or drillcollar I2.

The means 22 may be the same as the means 22 described above and mayconsist of a flexible element, such as a cord or wire 36, wrapped aboutthe bit shank and passed through slots 31 in the straps 2|. The ends ofthe wire 36 are tied or twisted together to dependably secure theprotector on the bit.

The use and operation of the protector illustrated in Figs. 3 and 4 arethe same as in the previously described form of the invention. Theprotector is applied to the bit before running the same into the welland is positioned so that its body 20ai and straps 2l fully shield theexposed parts of the cutters I5 and I 5. The straps 2| further serve toseal or close the spaces between the legs I3 and I4. When `the tool islowered through the well the protector prevents the ex-` posed toothedparts of the cutter from gathering or accumulating mud and effectivelyprevents the teeth of the cutters from gouging lor scraping the wall ofthe well. the bottom of the well it is put into operation. The protectoris quickly drilled up or reduced to small fragments which are carriedaway by the circulation fluid. The ridges 33 and the blade 34 assure thequick drilling up of the body 20a.

The present invention provides well bit Vprotectors that are veryinexpensive to manufacture and that are easily and quickly applied tothe bits. The protectors are formed to be readily shipped andtransported without danger of breakage and may be employed onpractically all forms of well bits.

Having described typical preferred forms and applications of myinvention, I do not wish to be limited or restricted to the specificdetails herein set forth, but wish to reserve to myself any variationsor modifications that may appear to those skilled in the art or fallwithin the scope of the following claims.

When the bit has ,reachedA Having 'described my invention, I claim:

1. `Aprotector for a well bit having toothed cutters, the protectorcomprising a ilexible drillable body for covering the cutters, and meansfor securing the body to the bit.

2. A protector for a Well bit having toothed cutters with exposed parts,the protector comprising a flexible drillable body for covering theunder sides of said parts, and means for securing the body to the bit.

3. A protector for a. well bit having toothed cutters with exposedparts, the protector comprising a drillable body for shielding the undersides of said parts, and straps extending upwardly from the body andtrained over the sides cof said parts to shield the same.

4. A protector for a well bit having toothed' cutters with exposedparts, the protector com' prising a drillable body for shielding theunder sides of said parts, flexible straps on the body adapted to betrained over the sides of said parts to shield the same, and meanscooperating with straps for securing the protector to the bit.

5. A protector for a well bit having roller cutters at its lower end,the protector comprising a flexible body to be engaged under the bitcover and shield the lower parts of the cutters, and

flexible parts extending upwardly from the body to be trained over theside parts of the cutters to shield the same.

6. A protector for a well bit having roller cutters at its lower end,the protector comprising a ilexible body to be4 engaged under the bitcover and shield the lower parts of the cutters. and

flexible strap-like parts integral with the body and adapted to betrained upwardly over the side parts of the cutters to shield the sameand to close the spaces between the cutters.

'7. A protector for a well bit having roller cutters at its lower end,the protector comprising a ilexible body to be engaged under the bitcover and shield the lower parts of the cutters, the body having a iiuidport, exible strap-like parts on the body adapted to be trained upwardlyover the side parts of the cutters to shield the same, and means engagedwith the strap-like parts for securing the protector to the bit.

8. 'A protector for a well bit having spaced cutters on its lower end.the protector comprising a sheet-like body of ilexible drillablematerial shaped to conform generally to the contour of the lower end ofthe bit and its cutters and adapted to be arranged against the lowerside of the bit to shield the cutters, the body having at least one portfor communicating with the space between the cutters.

, 9. A protector for a well bit having spaced cutters on its lower end,the protector comprising a sheet-like body of iiexible drillablematerial shaped toconform generally to the contour of the lower end ofthe bit and its cutter and to lie entirelywithin the cutting gauge ofthe cutters, and straps integral with the body to be trained upwardlyover the sides of certain of the cutters to shield the same.

10. A protector for a well bit having roller cutters on its lower end,the protector comprising a drillable body adapted to be engaged againstthe lower side oi the bit and having its margin shaped to conformgenerally to the contour of 'the periphery of the blt and its cutters, apart on the under side of the body for engaging the bottom of the wellto hold the body against turning, and means for securing the protectorto the bit comprising exible straps on the body to be trained upwardlyover the side portions of the cutters, and securing means for engagingwith the straps.

11. A protector for a well bit having roller cutters on its lower end,the protector comprising a drillable body adapted to be engaged againstthe lower side of the bit and having its margin shaped to conformgenerally to the contour of the periphery of the bit and its cutters,the body having at least one port'for passing iiuid through the bit, apart on the under side of the body for engaging the bottom of the wellto hold the body against turning, and means for securing the protectorto the bit comprising ilexible straps on the body to be trained upwardlyover the side portions of the cutters, and securing means for engagingwith the straps.

THOMAS E. MCMAHAN.

